Why does my alfa romero gtv idle erratically even when warm?

Because you should have bought a Fiat?

"Another View". Alfa Romeo, along with many other vehicles inc Fiat have numerous sensors witch help the engine run at its best. Most probable list goes : 1 idle sensor. 2 maf sensor. 3. variator. Best option is to get ECU analized witch will point out exactly witch sensor is At Fault or indeed some other problem.